Jimmy Carter says doctors find no new cancer growth

Doctors have found Jimmy Carter is responding well to treatment for cancer and report no evidence of new tumors, according to a statement released by the former U.S. president's spokeswoman on Tuesday.

Doctors at Emory University's Winship Cancer Institute told Carter "that recent tests have shown there is no evidence of new malignancy, and his original problem is responding well to treatment," spokeswoman Deanna Congileo said in the statement.

Tests will continue, she added.

Carter, 91, revealed in August that doctors had removed melanoma from his liver and discovered four small tumors on his brain. He received a radiation treatment targeted at those tumors and four doses of Keytruda, a newly approved drug to help his immune system seek out cancer cells appearing anywhere else in his body.

Dr. Sapna Patel, a melanoma specialist at the MD Anderson Cancer Center in Houston who has no role in Carter's treatment, said the statement gives "a lot of reason to be optimistic."

"We couldn't infer necessarily that the cancer is gone, but nothing is spreading, nothing is growing, nothing is worsening," she said. "This is considered really good news, if after a few short months, nothing is growing ... and there doesn't appear to be any new cancer."

The immune therapy likely will continue for one to two years as long as he is responding, she said.

Dr. Len Lichtenfeld, deputy chief medical officer for the American Cancer Society, said the doctors' report is "the best news possible" for a patient in Carter's situation. The statement doesn't mean Carter no longer has cancer but that doctors did not find any evidence of growth after a careful search, Lichtenfeld said.

"We certainly hope the president will continue on his current course," he said. "At this point, it appears his treatment has been as effective as possible."

Carter was the nation's 39th president, defeating Gerald Ford in the wake of Richard Nixon's resignation. He lost a bid for re-election four years later and focused on humanitarian work in the decades since.

Carter told The Associated Press earlier this month that he hadn't experienced any discomfort or illness following drug treatments for his illness, which were administered several weeks apart. Carter also said he has yet to scale back his work at The Carter Center, the human rights organization he founded after leaving the White House.

He has remained active during cancer treatment, including volunteering on a home-building project for Habitat for Humanity and acting as a mediator in a dispute between Martin Luther King Jr.'s children.